Passera Posted November 10, 2015 Share Posted November 10, 2015 I want to use an inverter in 12 volt socket when not on a campsite converting to 240v output. My inverter is max 175 watt. But the appliance I will use is rated at 100w My question is regarding amps. In calculating the amps I know it is watts divided by volts. Is my watts 175 or 100 and is the volts 12 or 240 when calculating. Hope it's not a silly question only a bit anxious about the a page rating of the wiring Tx Link to comment Share on other sites More sharing options...
Steve928 Posted November 10, 2015 Share Posted November 10, 2015 You will powering 100W from 12V so the current will be 100/12 = 8.5A, plus a bit for conversion losses etc. so 10A would be a safe estimate. The 175w max of your inverter would draw over 15A at 12V, so too much for the average cigarette lighter socket. Link to comment Share on other sites More sharing options...
Passera Posted November 10, 2015 Author Share Posted November 10, 2015 Tx Steve The sockets are in the habitation not cigarette lighter but I understand. I have asked rapido for amp limit and the reply was 100 watt!!!! So I guess the factory wiring should be 10 amp. Link to comment Share on other sites More sharing options...
tonyishuk Posted November 10, 2015 Share Posted November 10, 2015 I would suggest that any inverter should have its own dedicated fused circuit. Saves a lot of toasted wires and fuses if summat goes wrong. Rgds Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 11, 2015 Share Posted November 11, 2015 Passera - 2015-11-10 7:05 PM Tx Steve The sockets are in the habitation not cigarette lighter but I understand. I have asked rapido for amp limit and the reply was 100 watt!!!! So I guess the factory wiring should be 10 amp. I’m wary of Rapido’s reply to you. I notice that, on another forum thread, you say that you have a new Rapido 7065FF on order for delivery in February. The user-manual for my 2015 Rapido 640 indicates that the habitation-area 12V sockets for ALL current-model Rapidos are 20A-fused (so should be able to power a 240W 12V-appliance). In principle, then, you should be able to run your inverter at maximum output from a habitation-area 12V socket in your Rapido, and running a 100W-rated 12V appliance should be well within the sockets’ design capability. However, I’d echo Tony’s advice to provide a separate fused 12V supply (with chunky cabling) to power the inverter. Link to comment Share on other sites More sharing options...
lennyhb Posted November 11, 2015 Share Posted November 11, 2015 tonyishuk - 2015-11-10 7:25 PM I would suggest that any inverter should have its own dedicated fused circuit. Saves a lot of toasted wires and fuses if summat goes wrong. Rgds He is only talking about a tiny inverter, quite safe to plug into an existing socket. Link to comment Share on other sites More sharing options...
Passera Posted November 11, 2015 Author Share Posted November 11, 2015 Thank you again for all replies interesting about all Rapido having 20 amp fused. When you say chunk cabling Dereck please expand to a novice. How thick and rating. Would I be correct saying that though premiered it could be changed rather than put another dedicated socket in. Stalwart could be right and it's very useful to read all these opiniona Link to comment Share on other sites More sharing options...
aandncaravan Posted November 11, 2015 Share Posted November 11, 2015 In comparison to a 3000w Inverter it is small and the currents may not be huge, however can we advise a rethink? It isn't just the Socket that you are loading up, it is the Power Distribution/charger box that controls the flow of electricity around the vehicle. Generally Power Distribution/charger units are designed to supply fairly low currents split across multiple circuits. They generally don't need to be high current units because there is limited capacity in the battery. You are talking about asking the Power Distribution unit to supply current which is up near it's top end, possibly for a few hours, for example on a TV? The person saying it is ok to draw 20amps continuously is expecting a bit much from the Electronics and the battery? A 100Ah battery would be right down within just a couple of hours if that usage were actually applied. While this might be within the Power Distribution boxes design capability, it will be placing a significant power draw and load, that will most likely be greater than all the other 12v devices added together? When some of these Power Distribution/Chargers can cost up to £660, doesn't it make sense to give it as easy a life as possible? I would suggest the cheapest long term option will be to acquire a dedicated 12v appliance (TV?)? Not just because of the wear and tear on the distribution box, but reduced wear and tear on the battery. A dedicated 12v appliance won't have the overhead of the conversion losses of the Inverter ( which can be only 60% efficient), they are often optimised to run off a 12v battery and often more efficient generally. You will effectively increase your battery running time accordingly. A 40% drop in amps means 40% less wear on the battery and the Charger (either 240v or Alternator) that has to put it back. The figures may be exaggerated, but you see the principal. Link to comment Share on other sites More sharing options...
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